Question

Phineas is the lead research scientist in a lab and responsible for ordering supplies and equipment. The lab is out of petri dishes, so Phineas orders 185 of them. The lab uses 12 petri dishes each day.

Answer 1

The relationship is between the days that have gone by and the number of petri dishes.

The point (0, 185) means that if 0 days have gone by there are 185 petri dishes.

The number of petri dishes decreases by 12 each day, so the slope is –12.

Use the slope-intercept form to write the equation y = –12x + 185.

Answer 2

The answer is 12x + y = 185

The common formula for a two variable linear equation is: ax + by = r

The lab starts with 185 dishes which is y-intercept:
ax + by = 185

The number of dishes used per day is 12 which is slope:
12x +by = 185

Therefore, the two variable linear equation for this example is 12x + y = 185.