7/2x + 1/2x = 2 1/2 + 9/2x
solve.

x = -121

Step-by-step explanation:

(7/2)*x+(1/2)*x = (9/2)*x+121/2 // - (9/2)*x+121/2

(7/2)*x+(1/2)*x-((9/2)*x)-(121/2) = 0

(7/2)*x+(1/2)*x+(-9/2)*x-121/2 = 0

-1/2*x-121/2 = 0 // + 121/2

-1/2*x = 121/2 // : -1/2

x = 121/2/(-1/2)

x = -121

x = -3

y = -18

step-by-step explanation:

to solve by substitution, substitute one variable and solve for the other. then substitute again to find the remaining variable.

x-1/3(3x-9) = -3 since y=3x-9 substittute y.

x-1/3(3x-9)=-3

x + x +3 = -3

2x+3=-3

2x+3-3= -3-3

2x=-6

x=-3

substitute again into y=3x-9

y=3(-3)-9

y=-9-9

y=-18

sina-sinb

cosb+cosa

tana-tanb

cos0+cos x pi/3

20tan

step-by-step explanation: