Answer:
1,700mm
Explanation:
1,750mm=175cm
5cm=50mm
1,750-50=1,700mm
gary's project uses 1,750 which is equal to 175 cm he already has 5cm of string which is equal to 50mm so he will need 1,700mm of string or 170cm
i hope this helps please feel free to point out any mistakes that i might have made