The height is 1, because it's A=(b1 + b2)*h, the equation is this now 7=3 + 4)*h, you add 3 + 4 then that will give you 7, so now it should look like this 7=7*h, you do a fraction line under the 7 and 7*h each, and put a 7 as the denominator, so it kind of looks like this now 7 = 7*h __ __ 7 7 then you cancel the 7*h which leaves you to just h, so 7 divided by 7 will give you 1 so it looks like 1=h, PHEW
