12+12+9+9= 42
12 x 9= 108
12^2 x 9^2 =6561
( I hope I did that right for you )
(2) + (2)
=> 8x - 6y = -46 ———(3)
(1) + (3)
=> 5x + 6y + (8x - 6y) = 20 - 46
=> 13x + (6-6)y = -26
=> 13x + 0y = -26
=> 13x = -26
=> x = -26/13
=> x = -2
=> 5(-2) + 6y = 20
=> 6y = 20 + 10
=> 6y = 30
=> y = 5
x = -2, y = 5 => C
When will they blink together?
what is the smallest number they both mutiply to
3*5=15
so every 15 seconds
so at 15, 30, 45, 60 seconds
so 4 times if you count the time exactly at 1 minute
The answer is : multiply 5
