Idon't understand how to do it can someone me !

Which statement justifies why angle ebc measures 90?

3a + 5b - 7 = 0 a - 2b - 4 = 0 solve the system by the elimination method. check your work {(96/11, -5/11)} {(34/11, -5/11)} {(32/33, 5/11)}

Samuel deposited money in an account that’s pays an annual simple interest rate at 3.5%. at the end of 5 years, samuel earns $2625.00 in interest. how much money did he deposit in the account?