Final answer:
To find Shayna's weekly allowance, we can set up an equation based on the given information and solve for the unknown variable. The equation is (x/2) + 9 = 17, where x represents Shayna's weekly allowance. Solving the equation, we find that Shayna's weekly allowance is $16.
Step-by-step explanation:
To find Shayna's weekly allowance, we need to set up an equation based on the given information. Let's denote her allowance as x. We know that Shayna spent half of her allowance at the movies, so she has x/2 left. Additionally, she earned $9 by washing the dog. Therefore, her total amount is given by the equation (x/2) + 9 = 17. We can solve this equation to find Shayna's weekly allowance.
First, we can simplify the equation by subtracting 9 from both sides: (x/2) = 8. To get rid of the fraction, we can multiply both sides by 2, which gives us x = 16. Therefore, Shayna's weekly allowance is $16.