Question 972699
i usually solve these by finding a common variable and making everythign in terms of that common variable.


your equations are:


r = 5z
15z = 3y


the common variable appears to be z.


solve for z in both equations to get:


z = r/5
z = 3y/15


since r/5 = z and 3y/15 = z, then r/5 = 3y/15.


solve for r as follows:


r/5 = 3y/15
multiply both sides of the equation by 5 to get:
r = 3y/15 * 5 = y/5 * 5 = y
the equation simplifies to:
r = y


you can also just solve for one of the variables in terms of the other and then substitute for that variable.


start with:
r = 5z
15z = 3y


solve for z in terms of y to get:
z = 3y/15 = y/5


replace z with y/5 in the first equation to get:
r = 5 * y/5 which becomes:
r = y