Question

There are a total of 70 pebbles in Bag A and Bag B. There are a total of 120 pebbles in Bag B and Bag C. Bag C contains 3 times as many pebbles as Bag A. How many pebbles are there in Bag B?

There were 27 pineapple tarts and murukus. The ratio of the number of pineapple tarts to the number of murukus was 4:5. An equal number of each was given away and the ratio became 2:3. How many pineapple tarts were given away?

Answer 1

1. Eq1: A + B = 70. B = 70-A.

Eq2: B + C = 120.
Replace B with (70-A) and C with 3A:
(70-A) + 3A = 120
2A = 50
A = 25.

In Eq1, replace A with 25:
25 + B = 70
B = 45.

2. X Murukus tarts.
4x/5 Pineapple tarts.

X + 4x/5 = 27.
5x + 4x = 135
9x = 135
X = 15.

4x/5 = 60/5 = 12.

n = The # of each given away.
(12-n)/(15-n) = 2/3.
Cross multiply:
36 - 3n = 30 - 2n
n = 6 of each given away.