A man bought 42 stamps, some 13¢ and some 18¢. How many of each kind did he buy if the cost was $6.66?

1 answer:

OverLord2011 [107]3 years ago

5 0

Let's call the 13¢ stamps a and the 18¢ stamps b: a+b = 42 and therefore a= 42-b (formula 1) 0.13a+0.18b= 6.66 In this formula, substitute the value of a according to formula 1: 0.13(42-b)+0.18b= 6.66 Multiply on the left to get rid of the parenthesis: 5.46-0.13b+0.18b= 6.66 Subtract 5.46 from both sides: -0.13b+0.18b= 1.20 Add on the left: 0.05b= 1.20 Divide both sides by 0.05 b= 24 You have 24 18¢ stamps and: 42-24= 18 13¢ stamps Check: (24 x 0.18) + (18 x 0.13)= 6.66 Correct.

You might be interested in

ANYONE PLS HELPpppppppp!!

bezimeni [28]

Label the x-axis “Solo Practice Time (min)” and the y-axis “Number of baskets”.

label the graph as going up by 5s

Next, graph the points on the graph

7 0

3 years ago

X= r-h/y<br> solve for h and r

malfutka [58]

X = r - h/y ; Solve for h & r

Let's first solve for h :)

Add h/y to both sides.

h/y + x = r

So, r = h/y + x

Now, let's solve for h.

x = r-h/y

Subtract r from both sides.

-r + x = -h/y

Multiply both sides by y.

y(-r + x) = y(-h/y)

Simplify.

-ry + xy = -h

Divide both sides by -1.

ry - xy = h

So, h = ry - xy

~Hope I helped!~

3 0

3 years ago

Read 2 more answers

I invest £2,000 at a rate of 5% compound interest. I leave the amount 5 years. How much will I have after 5 years?

Lubov Fominskaja [6]

Answer:

£10,000 at a rate of 5%

5 0

3 years ago

Read 2 more answers

The circumference of a circle is 14π in. What is the area, in square inches? Express your answer in terms of \piπ.

Mama L [17]