Her brother is 8: 8 x 2 is 16, and 16 + 8= 24.
Just use your right angled triangle formula.
A=

Plug n chug
A=

A=71.5
Hey there
Lets solve this question together,
Convert 76.8% to a decimal.
0.768 * x=40.32
Multiply 0.768 by x to get 0.768x.
0.768x=40.32
Multiply each term by 1 / 0.768 and simplify.
Cancel the common factor of 0.768.
x=40.32 / 0.768
Divide 40.32 by 0.768 to get 52.5
x=52.5