Answer
In 1 set, they will be lifting the same weight.
They will be lifting the same weight when they are both lifting 21 kilograms.
Step-by-step explanation
Cody starts with 19 kilogram bar and increases this by 2 kilograms on each set.
In n sets, Cody will be lifting (19 + 2n) kilograms.
His partner, starts with 20 kilogram bar and increases this by 1 kilogram on each set.
In n sets, his partner will be lifting (20 + n) kilograms.
We are then asked to calculate when they will be lifting the same kilograms of weight.
When the amount of weight they are lifting becomes the same, we have,
19 + 2n = 20 + n
2n - n = 20 - 19
n = 1
So, in 1 set, they will be lifting the same weight.
when n = 1,
19 + 2n = 19 + 2(1) = 19 + 2 = 21 kilograms.
So, they will be lifting the same weight when they are both lifting 21 kilograms.
Hope this Helps!!!