Well, as you can see from the rectangle RT and SW should have equal lengths. So to find the value of x, we need to do.....
4x + 10 = 5x - 20
-x + 10 = -20 (Subtraction property of equality)
-x = -30 (Subtraction property of equality)
x = 30 (Division property of equality)
To check our work:
4(30)+10 = 130
5(30)-20 = 130
So, the value of x is 30!