-3x(x-10)=63

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-3x(x-10)=63
-3x(x-10)=63

-3x(x-10)=63
-3x^2+30x=63
-3x^2+30x-63=0
x^2-10x+21=0
(x-7)(x-3)=0
x-7=0 x=7
x-3=0 x=3

8x+y=88 8x+9(88-8x)=88 88x-8x=818-88 88x=888 x=9 y=88-8x=88-8*9=8 x=9 y=8 8.9x+8y=88 8 8x+8y=88 8x+8y=88 8x+8y=88 8y-8y=88-88 y=8 x=88-8y=88-8*8=8 x=8 y=8 8.8x+8y=88 8x+8y=8

-3X+30=63-3X=63-30
-3X=33
X=-11