1. **Problem statement:** We have an elastic band initially 20 cm long. Each increase of 1 newton in force stretches the band by 0.125 cm. 2. **Find the equation relating length $L$ to force $F$:** The initial length is $L_0 = 20$ cm. Each newton increases length by $0.125$ cm. The length $L$ as a function of force $F$ is: $$L = L_0 + 0.125F$$ 3. **Graph:** This is a linear function with slope $0.125$ and intercept $20$. 4. **Find the force when the band snaps at length $27.6$ cm:** Set $L = 27.6$ and solve for $F$: $$27.6 = 20 + 0.125F$$ Subtract 20 from both sides: $$27.6 - 20 = 0.125F$$ $$7.6 = 0.125F$$ Divide both sides by 0.125: $$F = \frac{7.6}{0.125} = 60.8$$ 5. **Answer:** The force that causes the band to snap is $60.8$ newtons.