Question

blake is saving up to buy a new pair of headphones. he has $20 saved already, and he earns $10 for every lawn he mows. how many lawns will he have to mow to have at least $90 saved?

Explanation:

Step1: Define variables and inequality

Let $x$ = number of lawns mowed. Total savings = initial savings + earnings from mowing. We need total savings $\geq 90$, so:
$$20 + 10x \geq 90$$

Step2: Subtract initial savings

Subtract 20 from both sides to isolate the term with $x$:
$$10x \geq 90 - 20$$
$$10x \geq 70$$

Step3: Solve for x

Divide both sides by 10 to find $x$:
$$x \geq \frac{70}{10}$$
$$x \geq 7$$

Answer:

Blake will have to mow at least 7 lawns.