Answer: y = - 466.375
Step-by-step explanation:
y varies jointly as x and z.
This means that y varies directly as x and also varies directly as z.
In order to remove the proportionality symbol, we will introduce a constant of proportionality, k. Therefore,
y = kxz
The next step is to determine the value of k
if y = 205 when x = –5 and z = –8.
we will substitute these values into the equation to determine k.
205 = k × -5 × -8
205 = 40k
k = 205/40 = 5.125
Therefore, the equation becomes
y = 5.125xz
We want to determine y when x = - 13 and z = 7
y = 5.125 × - 13 × 7
y = 5.125 × - 91
y = - 466.375
