If 21 is added to a number the result is 40 less than twice the number what is the number?

1 answer:

7 0

If 21 is added to (+ 21) a number (x) the result (=) is 40 less than (- 40) twice the number (2x)

x + 21 = 2x - 40 Add 40 to both sides
x + 61 = 2x Subtract x from both sides
61 = x Switch the sides to make it easier to read
x = 61

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How do I find X in this problem

pogonyaev

You know that BC is congruent to x so you need to solve for x using the ratio:
$\frac{12}{24}=\frac{x}{BC}$

So then we need to find BC.

We know:
$A=\frac{base \times height}{2}$
$28=\frac{BC \times 7}{2}$
Therefore BC =8

Then:
$\frac{12}{24}=\frac{x}{8}$
$x=8 \times \frac{12}{24} = 4$

4 0

3 years ago

Dont really understand

Llana [10]

Area is base times height, so take the 12 and 16 and multiply them, you will get 192 which is your answer

3 0

2 years ago

Read 2 more answers

Given: ABCD is a trapezoid, AC ⊥ CD AB = CD, AC=the square root of 75 , AB = 5 Find: AABCD

Ugo [173]

In this attached picture according to the conditions of the problem we have an isosceles trapezoid and since we know that legs are equal (AD=BC=5 cm), we have to calculate bases and height in order to find the area. Working with the triangle BCD, we apply Pythagoras theorem and find that CD = $\sqrt{75+25}$ = 10 cm. Since BDC is a right triangle, applying theorem for the area of triangles, we find that $\frac{1}{2} * BF = \frac{1}{2} * 5 * \sqrt{75}$ and BF= $0.5\sqrt{75}$ . Since ABCD is an isosceles trapezoid, triangles ADE and BFC are congruent with Angle Side Angle theorem. Then, DE=FC and with the help of Pythagoras theorem, DE=FC=2.5 cm. Then, AB=EF=5 cm and the area of the trapezoid is $A= BF * \frac{AB+CD}{2} = 0.5 \sqrt{75} * \frac{5+10}{2} = 18.75 \sqrt{3} cm^{2}$