Ineed on this one. give a workthrough so i can understand! i need the length of the third/missing side!

Graph red beads cost $1 an ounce and gold beads cost $3 an ounce. juanita wants to purchase a 12-ounce mixture of red and gold beads that she can sell for $2 an ounce. the solution of the system shows the number of beads needed for juanita to break even. x + y = 12, x + 3y = 24 how many ounces of red beads will juanita buy to break even? how many ounces of gold beads will she buy?

Given abcd ac=38 and ae=3x+4 find the value of x

Cody was 165cm tall on the first day of school this year, which was 10% taller than he was on the first day of school last year.