Answer:
It will take Greg 8 weeks to save up to buy the phone.
Step-by-step explanation:
Given equation is:
M = 90 + 15w
Here,
M represents the money saved
w represents the number of weeks
Greg wants to save 210
Putting M = 210 in the given equation;
210 = 90 + 15w
210 - 90 = 15w
15w = 120
Dividing both sides by 15
[tex]\frac{15w}{15}=\frac{120}{15}\\w = 8[/tex]
Hence,
It will take Greg 8 weeks to save up to buy the phone.