Answer:
1.46
Step-by-step explanation:
First find the the mean score before he made a 90.

Now add the score of 90 and calculate.

Subtract the two scores.

His mean test score increased by 1.46.
3x+5+10x-7=180
13x-2=180
-2 -2
13x=182
/13 /13
X=14
3(14)+5=47
10(14)-7=133
mm
The ratio in it's simplest form is 4:1.