-20/35 * 15/7 equal to in fraction form

A chemist has two alloys, one of which is 15% gold and 20% lead and the other which is 30% gold and 50% lead. How many grams of

vlabodo [156]

Answer: 490 grams of the first alloy should be used.

30 grams of the second alloy should be used.

Step-by-step explanation:

Let x represent the weight of the first alloy in grams that should be used.

Let y represent the weight of the second alloy in grams that should be used.

A chemist has two alloys, one of which is 15% gold and 20% lead. This means that the amount of gold and lead in the first alloy is

0.15x and 0.2x

The second alloy contains 30% gold and 50% lead. This means that the amount of gold and lead in the second alloy is

0.3y and 0.5y

If the alloy to be made contains 82.5 g of gold, it means that

0.15x + 0.3y = 82.5 - - - - - - - - - - - -1

The second alloy would also contain 113 g of lead. This means that

0.2x + 0.5y = 113 - - - - - - - - - - - - -2

Multiplying equation 1 by 0.2 and equation 2 by 0.15, it becomes

0.03x + 0.06y = 16.5

0.03x + 0.075y = 16.95

Subtracting, it becomes

- 0.015y = - 0.45

y = - 0.45/- 0.015

y = 30

Substituting y = 30 into equation 1, it becomes

0.15x + 0.3 × 30 = 82.5

0.15x + 9 = 82.5

0.15x = 82.5 - 9 = 73.5

x = 73.5/0.15

x = 490

6 0

3 years ago

2.1 x 10^10 OVER 7 x 10^17

vlabodo [156]

2.1 x 10^10/ 7 x 10^17
= 3 x 10^-8

hope this helps and have a great day :)

4 0

3 years ago

Read 2 more answers

Alex must read at least 500 pages of his book this month. He has already read 260 pages. If he reads 30 pages a day, what is the

slamgirl [31]

So he has to read 500 and he already read 260 500 - 260 = 240. 240 divided by 30 equals 8. So the answer will be 8 days

5 0

2 years ago

What's the surface area ratio & the volume ratio??<br><br> please help me ASAP!!

Ulleksa [173]

Answer:

Step-by-step explanation:

Volumes of two spheres A and B = 648 cm³ and 1029 cm³

Things to remember:

1). Scale factor of two objects = $\frac{r_1}{r_2}$ [ $r_1$ and $r_2$ are the radii of two circles]

2). Area scale factor = $\frac{(r_1)^2}{(r_2)^2}$

3). Volume scale factor = $\frac{(r_1)^3}{(r_2)^3}$

Volume scale factor Or Volume ratio = $\frac{V_A}{V_B}$

$\frac{(r_1)^3}{(r_2)^3}= \frac{648}{1029}$

$\frac{r_1}{r_2}=\sqrt[3]{\frac{648}{1029} }$

$\frac{r_1}{r_2}=\frac{6(\sqrt[3]{3})}{7(\sqrt[3]{3})}$

$\frac{r_1}{r_2}=\frac{6}{7}$

Therefore, scale factor = $\frac{r_1}{r_2}=\frac{6}{7}$

≈ 6 : 7

Area scale factor Or area ratio = $(\frac{r_1}{r_2})^2=(\frac{6}{7})^2$

= $\frac{36}{49}$

≈ 36 : 49

Volume scale factor or Volume ratio = $\frac{648}{1029}$

= $\frac{216}{343}$

≈ 216 : 343

4 0

3 years ago

30. What is the solution to the system of equations?

sukhopar [10]

Answer:

x = 3

y = 0

z = 8

Step-by-step explanation:

a) 3x + 3y - z = 1

b) z = 8

c) -x -3y + 2z = 13

a) 3x + 3y - 8 = 1 (substitution)

a) 3x + 3y = 9

c) - x - 3y + 2(8) = 13 (substitution)

c) -x - 3y + 16 = 13

c) -x - 3y = -3

(3x + 3y = 9) + (-x -3y = -3)

= 2x = 6

x = 3

a) 3(3) + 3y - 8 = 1

9 + 3y - 8 = 1

y = (1 -9 + 8)/3

y = 0

5 0

3 years ago