Equation : x + y = 170 and y = 2x - 40
The weight of Bill is 70 pounds and weight of mark is 100 pounds
Solution:
Let the weight of Bill be "x"
Let the weight of mark be "y"
Given that,
Mark and Bill have a combined weight of 170 pounds
Therefore,
x + y = 170 ------- eqn 1
Mark weighs 40 pounds less than twice Bill's weight
y = 2x - 40 ------- eqn 2
Substitute eqn 2 in eqn 1
x + 2x - 40 = 170
3x = 170 + 40
3x = 210
x = 70
Substitute x = 70 in eqn 2
y = 2(70) - 40
y = 140 - 40
y = 100
Thus weight of Bill is 70 pounds and weight of mark is 100 pounds