given that
A= 1/2 ( a+b )h
the L . C . M for this equation is 2
multiplying through with the L .C .M
2×A = 1/2 ×2 ( a +b )h
2A = ( a + b ) h
dividing through by ( a+b )
thus
2A/(a +b ) = (a + b )h/ ( a + b )
when you cancel out the a + b
you will get
h =2A/( a+b ). as your final expression .
