Let us assume the number of times Bill saved $75 from his paycheck = x
Let us assume he number of times Bill saved $150 from his paycheck = y
Since he saved 75$ or 150$ for the 8 paychecks.
So, x+y=8
y=8-x (Equation 1)
Since Bill saved $825 from his last 8 paychecks using $75 or $150.
So, 75x+150y=825 (Equation 2)
Substituting the value of 'y' from equation 1 in equation 2,
![75x+150(8-x)=825](https://img.qammunity.org/2019/formulas/mathematics/high-school/72woev7a0y948ok5xvr8ow29dmzbzeiv6p.png)
![75x+1200-150x=825](https://img.qammunity.org/2019/formulas/mathematics/high-school/wj5xx0tljdh278nystgttlt1fwhtn9qup6.png)
![75x-150x=825-1200](https://img.qammunity.org/2019/formulas/mathematics/high-school/dqzhwyy2yuv5xpvm2h38syl8ppr1pkq3uz.png)
![-75x=-375](https://img.qammunity.org/2019/formulas/mathematics/high-school/a1wc285tfy6j274pp26ue3utcxm75cq509.png)
x = 5
Therefore, Bill saved $75, 5 times from his paycheck.