The LCD (lowest common denominator) is the lowest common denominator of two or more fractions.
4 = 2²
16 = 2⁴
8 = 2³
Take common and non-common factors with highest exponent.
So LCD = 16
The new dneominator of all fractions is 16. Divide this number for the original denominators and multiply for numerator...
16/4 = 4
4*3 = 12
3/4 = 12/16
16/16 = 1
1*7 = 7
7/16 = 7/16
16/8 = 2
2*5 = 10
5/8 = 10/16