The number A is 35% of the number B, and the number B is 48% of the number C.

The number A is 35% of the number B, and the number B is 48% of the number C. What percentage is the number A + B of the number C?

Let us express the number A through the number B using the proportion:
B = 100%;

A = 35%.

Using the main property of proportion, crosswise, we express the number A:

A = (35 * B) / 100 = (7 * B) / 20.

Let us express the number B through the number C using the proportion:
C = 100%;

B = 48%.

Using the main property of proportion, crosswise, we express the number B:

B = (48 * C) / 100 = (12 * C) / 25.

Let’s find the sum of numbers A and B:
A + B = (7 * B) / 20 + (12 * C) / 25 = (7 * (12 * C) / 25) / 20 + (12 * C) / 25 = (7 * 12 * C) / 25 * 1/20 + (12 * C) / 25 = (84 * C) / 500 + (12 * C) / 25 = (84 * C) / 500 + (240 * C) / 500 = (84 * C + 240 * C) / 500 = (324 * C) / 500 = (81 * C) / 125.

Let’s make a proportion and solve it:
C = 100%;

(81 * C) / 125 = x.

Find x:

x = ((81 * C) / 125 * 100) / C = (81 * 100 * C) / 125: C = (8100 * C) / 125: C = 64.8%.

Answer: 64.8%.