163.2 is the correct Answer
No values of z make the equations true.
You divide 690 by 100 which is 6.9
Therefore, one 50cent coin is 6.9g
Okay so first you want to simplify the given equation (7x+3y)(7x-3y)
in order to do this you multiply the first number of the first equation (7x) with the first number of the second equation (7x) this gives you 49x^2
Now you want to multiply the second number of the first equation (3y) by the second number of the second equation (-3y) this gives you -9y^2
Its as easy as pie!
The answer should be 380/0.5 =760 speed
