Solve the system of linear equations by substitution for x and y 1. X+y=7
Y=-3

2. 3x+4y=-10
X=-3y

(10,5)

Step-by-step explanation:

●x+(-3)=7

x=7+3

x=10

●3x+4y=-10

3(-3y)+4y=-10

-6y+4y=-10

-2y=-10

y=5

3.4 pizzas

step-by-step explanation:

given is a scatter plot showing number of pizzas sold during weeks for different issues of coupon

y represents number of pizzas sold and x number of coupons issued

y is marked verticaly and x horizontally

the trend line is given as

y =3.4x+43

this says that even when no coupon is issued pizzas sold will be 43

and rate of change of pizza sold for 1 unit of coupon = slope = 3.4

i.e. when x increases by 1 unit y increases by 3.4 units

hence for each additional coupon issued 3.4 pizzas more will be sold

i believe the answer is the polygon, heptagon.