Answer:
Scores are Joe = 78
Tom = 85
Nick = 68
Explanation:
Let us take Joe, Tom and Nick's score as a, b,c respectively.
We have combined score = 231
a + b + c = 231 ----------------------------------Equation 1
Joe’s score was 10 more than Nick’s score
a = c + 10
a - c = 10 ----------------------------------Equation 2
Tom’s score was 7 more than Joe's score
b = a + 7
b - a = 7 ----------------------------------Equation 3
Equation 1 + Equation 2 gives
a + b + c + a - c = 231 + 10
2a + b = 241 ----------------------------------Equation 4
Equation 4 - Equation 3 gives
2a + b -( b - a) = 241 - 7
3a = 234
a = 78
Substituting in equation 3 and equation 2,
b - 78 = 7
b = 85
78 - c = 10
c = 68
So scores are Joe = 78
Tom = 85
Nick = 68