We know that the formula to solve for the area of a trapezoid is A=(a+b)/2+h. So, the formula to find the height would be 2*[A/(a+b)].
2*[A/(a+b)] Substitute the values for the variables
2*[30/(4.8+5.2)] Solve the parentheses
2*(30/10)
2*3=6
The height must be 6 inches.