Anyone Know The Answer???

At a pizza shop 70% of the customers order a pizza 25% of the customers order a salad and 15% of the customers order both a pizza and a salad if s customer is chosen at random what is the probability that he or she orders either a pizza or a salad

You use technology ans find a sum of 6.712e-8. write this sum in standard form

Ranck the following in order from least precise to most precise