Question

What is the value of x?

Answer 1

Answer:

x=9

Step-by-step explanation:

We can use similar triangles and ratios.  Put the small triangle side over the large triangle side.

9cm            3x -20

----------   = ----------------    We need to add the sides to get to the larger triangle

72+9 cm   3x-20 + 56

We can cross multiply to solve

9 * (3x-20+56) = (72+9) * (3x-20)

Simplify

9*(3x+36) = 81*(3x-20)

Distribute

27x +324 = 243x -1620

Subtract 27x from each side

27x-27x +324 = 243x-27x -1620

324 = 216x-1620

Add 1620 to each side

324+1620 = 216x

1944 = 216x

Divide each side by 216

1944/216 = 216x/216

9=x

Answer 2

Answer:

im not great at math but i think x=9

Step-by-step explanation:

9/72=0.125

72*0.125=9

so 56*0.125=7

therefore 3x-20=7

solve for x

3x - 20 = 7  

3x = 7 + 20  

3x = 27 (divide both sides by 3 to get x)  

3x/3 = 27/3  

x = 9  

......

.......

or you can try

56/72=0.77777777777

72*0.77777777777=56

so 9*0.77777777777=7

therfore 3x-20=7

solve for x

3x - 20 = 7  

3x = 7 + 20  

3x = 27 (divide both sides by 3 to get x)  

3x/3 = 27/3  

x = 9