Can someone help me will give brainliest thanks (:

First set it up as an inequality using x and y as the amount of coins

10x + 20y = 690

Now get x by itself on one side by subtracting y

10x = 690 - 20y

Divide by 10 on both sides

X = 69 - 2y

Now plug this value for x into a separate equation just showing the amount of coins
(X+y=45)

69 - 2y + y = 45

Now solve for y

69 - y = 45

-y = -24

Y = 24

Now plug this y value into the same equation to solve for x

X + 24 = 45

X = 21

To check this work add both values into the original equation and solve

10(21) + 20(24) = 690

210 + 480 = 690

690 = 690