Let the player has x hits in y at-bats.
Since players initial average is 0.256, therefore, we can set up an equation:
![(x)/(y) =0.256](https://img.qammunity.org/2019/formulas/mathematics/middle-school/57kn9tsx17s5q1bv617srjzmvo6af38i1r.png)
Further, we are given that player hits 12 in 35 at-bats. Therefore, the total hits are now
and total at-bats are now
.
Since the new average becomes 0.275, therefore, we can set up:
![(x+12)/(y+35) =0.275](https://img.qammunity.org/2019/formulas/mathematics/middle-school/g7ad5fkx0s8jk6mxux2125e9yzj3qj8o3c.png)
Our next step is to solve these two equations and get values of x and y.
![(x)/(y)=0.256\Rightarrow x=0.256y\\ (x+12)/(y+35)=0.275\Rightarrow x+12=0.275y+9.625\\](https://img.qammunity.org/2019/formulas/mathematics/middle-school/ieh0dksif52yter08lbxvtmwqdh4clln46.png)
Upon using substitution method, we get:
![0.256y+12=0.275y+9.625\\ 0.275y-0.256y=12-9.625\\ 0.019y=2.375\\ y=(2.375)/(0.019)=125](https://img.qammunity.org/2019/formulas/mathematics/middle-school/nb3r1yo3j9ohkvajyrmjdnjo39ma1atgdo.png)
We can find the value of x by substituting this value of y in the first equation.
![x=0.256(125)\Rightarrow x=32](https://img.qammunity.org/2019/formulas/mathematics/middle-school/c656a5offszkagsdvrvo9cwmkq99g843e0.png)
Therefore, player made 32 hits in 125 at bats.