Replace $x$ and $y$ in $y=0.8x+5$ using your conversion equations so the result involves only $c$ and $t$.

Since centimeters are 100 times smaller than meters, and minutes are 60 times larger than seconds, the new slope should be much smaller than $0.8$.

Enter the expression

$t=(0.8*(c/100)+5)/60$

This directly applies $x=\frac{c}{100}$ and then converts $y$ seconds to $t$ minutes by dividing by 60.

Create a table with a few $c$ values (for example, $c=0$ and $c=7500$) and compute the corresponding $t$ from the expression.

From the table, note the value of $t$ when $c=0$ (the intercept) and how much $t$ changes when $c$ increases by $7500$ (this reveals the slope). Choose the option whose intercept and slope match these observations.

From $c=100x$, we have $x=\frac{c}{100}$.

From $t=\frac{y}{60}$, we have $y=60t$.

Substitute $x=\frac{c}{100}$ and $y=60t$ into $y=0.8x+5$:

Simplify and divide by $60$:

Convert to fractions:

• $\frac{0.008}{60}=\frac{8/1000}{60}=\frac{8}{60000}=\frac{1}{7500}$
• $\frac{5}{60}=\frac{1}{12}$

Therefore, the line of best fit relating $t$ to $c$ is $t=\frac{1}{7500}c+\frac{1}{12}$.