Oliver, Cole and Fabian had some pens in the ratio of 3 : 4 : 7. Fabian gave 40% of his pens to Oliver and Cole. As a result, Oliver had the same number of pens as Cole and Fabian had 21 fewer pens than Oliver.

1. What was the percentage increase in Oliver's pens after receiving from Fabian?
2. How many pens did Cole have at first?

Oliver	Cole	Fabian	Total
3 u	4 u	7 u	14 u
+ 2.8 u		- 2.8 u
4.9 u	4.9 u	4.2 u	14 u

(a)
Number of pens that Fabian gave away
= 40% x 7
= ⁴⁰₁₀₀ x 7
= 2.8 u

Number of pens that Oliver and Cole each had in the end
= (14 u - 4.2 u) ÷ 2
= 9.8 u ÷ 2
= 4.9 u

Increase in the number of pens that Oliver had
= 4.9 u - 3 u
= 1.9 u

Percentage increase in Oliver's pens after receiving from Fabian
= ^1.9₃ x 100%
= 63.333333333333%

(b)
4.9 u = 4.2 u + 21
4.9 u - 4.2 u = 21
0.7 u = 21

1 u = 21 ÷ 0.7 = 30

Number of pens that Cole had at first
= 4 u
= 4 x 30
= 120

Answer(s): (a) 63.333333333333%; (b) 120