3x − 4y = 12
2x + 6y = 18

Choose all of the equations that could be used when solving this system by substitution.

x = 9 − 3y
y = 18 − 3x
y = 3x + 3
x = 4
3
y + 4

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Can you me find the slope! (30 points)

Astudent must have an average on five test that is greater than it equal to 80% but less than 90% to receive a final grade of b. devon's greades on the first four test were 78% 62% 91% and 80% what range if grades on the fifth test would give him a b in the course? ( assuming the highest grade is 100%)