Step-by-step explanation:
Given Richardson sat for a math Olympic exam that had 25 questions for every right question he earn 10 points and for every wrong he lost 2.5 points.
Let , he got x questions right .
Number of wrong question is (25-x)
According to the problem,
[tex]x\times 10 -(25-x)2.5 = 150[/tex]
[tex]\Leftrightarrow 10x -62.5+2.5x = 150[/tex]
[tex]\Leftrightarrow 12.5 x = 150 +62.5[/tex]
[tex]\Leftrightarrow 12.5 x = 212.5[/tex]
[tex]\Leftrightarrow x =\frac{ 212.5}{12.5}[/tex]
[tex]\Leftrightarrow x = 17[/tex]
Therefore he got 17 questions right.