Help me once again and again

You are at a restaurant and owe $56.20 for your meal. you want to leave an 18% tip. approximately how much is your tip?

Atriangle has a side lengths of 18cm, 80 cm and 81cm. classify it as acute obtuse or right?

Girardo is using the model below to solve the equation . girardo uses the following steps: step 1 add 4 negative x-tiles to both sides step 2 add 1 negative unit tile to both sides step 3 the solution is which step could be adjusted so that gerardo's final step results in a positive x-value? in step 1, he should have added 4 positive x-tiles to both sides. in step 1, he should have added 3 negative x-tiles to both sides. in step 2, he should have added 4 negative unit tiles to both sides. in step 2, he should have added 1 positive unit tile to both sides.