We know that a right angle is 90 degrees. So we can make the equation Now, we can solve fore X! We can combine 35 and 7 to make the equation . In order to isolate x we have to subtract 42 from both sides, getting us the equation Now, in order to isolate x we must divide each side by 4, getting us the equation . To prove that x=12, we can subsitute x for 12. This means that we can do which simplified, is 90=90, making x=12 true. Hope this helps :)
