The formal formula for calculating the number given a percentage is:
n = (t/100)*p, where
t is the total number of pies and p is the percentage of the total.
Therefore,
n = 1550/100 * 30 = 465
A short cut is to express the percentage as a fraction: 30% = 0.3, and simply multiply the total by this fraction:
1550 * 0.3 = 465
