x= brother's height
Multiply 2/3 by the brother's height (x). This equals the sister's 48 inch height.
2/3x= 48
divide both sides by 2/3
x= 48 ÷ 2/3
multiply by the reciprocal of 2/3
x= 48 * 3/2
x= (48*3)/2
x= 144/2
x= 72 inches, the brother's height
ANSWER: The brother is 72 inches tall.
Hope this helps! :)