Answer: Arm routine = 11 minutes
Abdominal routine = 22 minutes
Explanation:
Let the minutes used for an arm routine be represented by x.
Let the minutes used for an abdominal routine be represented by y.
Last week, he worked out for a total of 88 minutes by doing 2 arm routines and 3 abdominal routines. This can be expressed as:
2x + 3y = 88
This week, he has completed 4 arm routines and 1 abdominal routine and spent a total of 66 minutes exercising. This can be expressed as:
4x + y = 66
2x + 3y = 88 ...... i
4x + y = 66 ...... ii
Multiply equation I by 4
Multiply equation ii by 2
8x + 12y = 352 ...... iii
8x + 2y = 132 ...... iv
Subtract iv from iii
10y = 220
y = 220 / 10
y = 22
An abdominal routine last for 22 minutes
From equation I
2x + 3y = 88
2x + 3(22) = 88
2x + 66 = 88
2x = 88 - 66
2x = 22
x = 22/2
x = 11 minutes
An arm routine last for 11 minutes