Problems based on Numbers Test 3

The total number of questions = 200
In which, Mathematics, G.K and Science has 50, 100 and 50 numbers of questions, respectively.
Total time = 3 hours = 180 minutes
Time taken by Gita to solve question of G.K. and science = x
Time spent on Mathematics questions = 2x.
According to the statement,
$150\left(\mathit{x}\right)+50\left(2\mathit{x}\right)=180$
$150\mathit{x}+100\mathit{x}=180$
$250\mathit{x}=180$
$\mathit{x}=\frac{180}{250}=0.72$ minute.
Time spent by Gita on Mathematics questions = 50.
$\left(2\mathit{x}\right)=50\left(2\times 0.72\right)=72$ minutes.