To solve the equation \( 5.6(x + 1.42) = 7.8 \), the first step should be to simplify the equation by isolating \( x \). The best first step in this case is to divide both sides of the equation by \( 5.6 \).
So, the correct first step is:
Divide both sides by 5.6.
After that, you can proceed to solve for \( x + 1.42 \) and then isolate \( x \).