Answer:
75 weeks
Step-by-step explanation:
Let the number of weeks be x
10x + 45 = 789 Subtract 45 from both sides
10x = 789 - 45 Combine
10x = 744 Divide by 10
x = 744/10 Divide
x= 74.4 weeks. It will not hurt her to save the extra week to get the phone
10^2x²-3=10^9-x²
by comparison,
2x²-3=9-x²
3x²=12
x²=4
x= 2 or -2
YOUR ANSWER MIGHT BE 2