Simultaneous Equations - How to form the equation

Juanita saves 20 cent and 50 cent coins in a money jar. After counting her money, she has 299 coins in total which ass up to $94.

I) Taking x to be the number of 20 cent coins and y to be the number of 50 cent coins, write down two equations in x and y to represent this information.

Im just struggling trying to form the equation, I can solve it after that.

I think it would be something like this

20x + 50y = 299

20x + 50y = 940

I was thinking along these lines, Can somebody help?

But then when you change the signs, you cross out both the x and the y, Its confusing me.