Question

There are black,green,yellow counters in a bag in the ratio 3:10:7

there are 105 yellow counters
how many black counters are there

Answer 1

There are 45 black counters.
If yellow = 7, but also has the real value of 105, we do 105/7 which gives us 15.
we then do 15 x 3 which gives us 45