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Could someone help me with these math problems? I can't figure them out. Solve the linear equation;
x+2y=15
y=-2x+0 9x-12y=-3
-12x+16y=4? =B y I y is an integer and ≤−4 7^(x+1) + 7^x + 7^(x-1) = 399, what is x? Diameter of a wheel 80cm. If the wheel rotates through an angle of 200degrees, how many cm does it move? Show steps please!? What day will it be exactly 6 months from June 14th, 2017? Best answer gets buncha stars?