Xy is the number
A) x + y = 7
B) 10y + x = 10x + y + 9
collecting terms of equation B
B) -9x + 9y = 9
multiplying A) by 9
A) 9x + 9y = 63 then adding it to equation B)
B) -9x + 9y = 9
18y = 72
y = 4
x = 3
The number is 34
784 divide by 7 is 112 so answer 112
You just have to make 36/10 into 3 6/10. After that, it would become 3.6
(2x - y = -2)2
5x - 2y = -7
4x - 2y = -4
Subtract both
x = -3
5(-3) - 2y = -7
-15 - 2y = -7
-2y = 8, y = -4
Solution: (-3,-4)