x = 1st number, y = 2nd number, z = 3rd number
x + y + z = 45
x = y + 10......x - 10 = y
x = 3z......1/3x = z
x + x - 10 + 1/3x = 45
2 1/3x - 10 = 45
7/3x = 45 + 10
7/3x = 55
x = 55 / (7/3)
x = 55 * 3/7
x = 165/7
x - 10 = y
165/7 - 10 = y
165/7 - 70/7 = y
95/7 = y
1/3x = z
1/3(165/7) = z
165/21 = z
55/7 = z
check...
x + y + z = 45
165/7 + 95/7 + 55/7 = 45
315/7 = 45
45 = 45 (correct)
so, x = 165/7
y = 95/7
z = 55/7
