AI Tutor
Imagine you have 15βˆ—βˆ—inyourpiggybank,andeveryFridayyouearnβˆ—βˆ—15** in your piggy bank, and every Friday you earn **8 doing yard chores.
If a brand-new skateboard costs $63, how many weeks will you need to work before you can buy it?

Turning Words into Rules

A variable is a letter that stands for an unknown number, like xx for weeks and yy for total money.
When a pattern adds a repeating amount every time, we multiply that repeat rate by xx and add our starting amount.
Since each week brings 8βˆ—βˆ—,savingfor8**, saving for xweeksgivesweeks gives8 \times x(or(or8x).Addingthestartingβˆ—βˆ—). Adding the starting **15$ gives our equation: y=8x+15y = 8x + 15
How do we use this equation to solve our multi-step problem and find the exact number of weeks?

Solving Multi-Step Problems

To find when your savings equal **63βˆ—βˆ—,replacethetotal63**, replace the total ywithwith63$: 63=8x+1563 = 8x + 15
First, subtract the starting 1515 from both sides to find how much money still needs to be earned: 63βˆ’15=4863 - 15 = 48.
Next, divide the remaining 48βˆ—βˆ—bytheweeklyrateofβˆ—βˆ—48** by the weekly rate of **8: 48Γ·8=648 \div 8 = 6 weeks.