Question

9.
0.9(3x + 6) = 5.4 - 3(0.1x + 21)

x = 2.1 \t x = -2.1 \t x = -21
tan \t purple \t brown

Explanation:

Step1: Expand both sides

Expand the left - hand side: $0.9(3x + 6)=0.9\times3x+0.9\times6 = 2.7x+5.4$
Expand the right - hand side: $5.4-3(0.1x + 21)=5.4-(3\times0.1x+3\times21)=5.4-(0.3x + 63)=5.4 - 0.3x-63=-0.3x - 57.6$
So the equation becomes $2.7x + 5.4=-0.3x-57.6$

Step2: Move terms with x to left and constants to right

Add $0.3x$ to both sides: $2.7x+0.3x + 5.4=-0.3x + 0.3x-57.6$, which simplifies to $3x+5.4=-57.6$
Subtract 5.4 from both sides: $3x+5.4 - 5.4=-57.6 - 5.4$, so $3x=-63$

Step3: Solve for x

Divide both sides by 3: $\frac{3x}{3}=\frac{-63}{3}$, so $x=-21$

Answer:

x = -21