(3x+4y=18) (5x+6y=28)

x = 2, y = 3

Step-by-step explanation:

Given the 2 equations

3x + 4y = 18 → (1)

5x + 6y = 28 → (2)

Multiplying (1) by 5 and (2) by - 3 , then adding will eliminate the term in x

15x + 20y = 90 → (3)

- 15x - 18y = - 84 → (4)

Add (3) and (4) term by term to eliminate x

2y = 6 ( divide both sides by 2 )

y = 3

Substitute y = 3 into either of the 2 equations and solve for x

Substituting into (1)

3x + 4(3) = 18

3x + 12 = 18 ( subtract 12 from both sides )

3x = 6 ( divide both sides by 3 )

x = 2

Solution is (2, 3 )

the sum of all the angles in a triangle are equal to 180

so you can add   the 3 given angles together to equal 180:

5y + 2y + 2y = 180

or since all three angles have the same letter, combine the 3 angles to equal 180:

9y = 180