Peter had 4 times as many pencils as Tom. When Tom's sister gave him 48 more pencils,
he had 1/2 as many pencils as Peter.
(a) How many pencils did Tom have in the end?
(b) How many pencils did the boys have altogether in the end?
Let the number that Tom had = T
Then Peter had 4T
When tom got 48 pencils, Tom only had twice as many
2 *(T + 48) = 4T
2T + 96 = 4T
96 = 4T - 2T
96 = 2T
96/2 = T = 48
a ) Tom had 48 + 48 = 96 at the end
b ) Peter had 4 (48) = 192
Together, they had 96 + 192 = 288
credit to cphill