Question

How would I find out what the variable “h” is??

Answer 1

Similar Triangle
The small triangle and the large triangle are similar triangles. They have the same proportion in the corresponding side. We could solve h by making a comparison of base-hypotenuse.
$\dfrac{\text{base}}{\text{hypotenuse}} = \dfrac{\text{base}}{\text{hypotenuse}}$

In this case, we could write it as:
$\dfrac{\text{large base}}{\text{large hypotenuse}} = \dfrac{\text{small base}}{\text{small hypotenuse}}$

Input the numbers into the formula above
$\dfrac{h}{280+70} = \dfrac{20}{280}$
Simplify the fraction
$\dfrac{h}{350} = \dfrac{20:20}{280:20}$
$\dfrac{h}{350} = \dfrac{1}{14}$
Do cross multiplication
14 × h = 350 × 1
14h = 350
    h = 350/14
    h = 25

The value of h is 25