Carter has two test grades of 83, four grades of 86, and 3 grades of 92 on his first nine math tests. His final exam will be weighted as three test grades, write an equation that shows that Shakiraquan's final grade for the term will be 88?

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Answer 1 · 2018-06-09T03:07:35

$\frac{2 (83) + 4 (86) + 3 (92) + 3 x}{12} = 88$ $(2(83)+4(86)+3(92)+3x)/12 = 88$

He would need to score $90$ $90$ on the final to earn an $88$ $88$ in the class.

$\frac{2 (83) + 4 (86) + 3 (92) + 3 x}{12} = 88$ $(2(83)+4(86)+3(92)+3x)/12 = 88$

$\frac{166 + 344 + 276 + 3 x}{12} = 88$ $(166+344+276+3x)/12 = 88$

Use the multiplicative inverse to eliminate the denominator

$cancel 12 * (166+344+276+3x)/cancel12 = 88*12$

$166+344+276+3x = 1056$

$786 +3x = 1056$

Use the additive inverse to isolate the variable term

#cancel786 +3x cancel (-786)= 1056-786

Use the multiplicative inverse to isolate the variable

$((cancel3)x)/cancel3 = 270/3$

$x = 90$