Find the value of x in the system, using substitution y=2x; 4x-y=-4

Find the solution of this system of equation -7x+y=-20 9x-3y=36

Can someone me do math because i am having a breakdown rn because i don’t get it

Three people are traveling and need to exchange the currency of their native country for the currency of the country they are visiting. drag each exchange to the category that shows the ratio of currencies in that exchange.