X+Y+Z = 15- 1 formula Y+Z = 15-X-2 formula

x+5y+ 10z = 70 x+5(y+z)+5Z = 70 x+5( 15-x)+5Z = 70

75-4x+5z=70

5+5z=4x，5( 1+z)=4x

(x, z < =10) and is an integer; 4x can be divisible by 5, so x=5 or x= 10.

When x=5, z = 3 and y = 7;

When x= 10, z = 7 and y = 3 do not conform to formula 2.

So x = 5, y = 7 and z = 3.