Which equation combines with the given equation to form a system of equations with the solution x = 3 and y = 9? x + 2y = 21

x + 2y = 21

Step-by-step explanation:

Even other options have not been given in this question, But we will prove that equation that combines to form a system of equations is x + 2y = 21

For this we will prove this equation true for x = 3 and y = 9

x + 2y = 21

3 + 2×9 = 21

3 + 18 = 21

21 = 21

Therefore, equation x + 2y = 21 combines to form a system of equations.

i only know the sequence of arithmetic it adds the first is 5+4 then it goes up as it adds to then it is 9+5 then 14+6 then to 20+7 and so on. 5,9,14,20,27,35.

step-by-step explanation:

it is 10.6 according to my calculations