I need help coming up with what equation I should use

Specification 03-Calculating Postage Prof. Lambiase We will be determining the postage cost for regular or large envelopes ounces. The chart below shows the rates not weighing more than 3 Weight Not Over (oz) RegularLarge 0.55 0.70 0.85 1.00 1.15 1.30 program will input values until a weight less than O ot greater than 3 ounces is entered. Postage Calculations What is the weight of the letter, in ounces? 0.3 What is the size of the letter? (L large, R regular) The postage for a regular letter weighing 0.30 ounces is $ 0.55 What is the weight of the letter, in ounces? 0.6 What is the size of the letter? (L - large, R regular) The postage for a large letter weighing 0.60 ounces is 1.00 What is the weight of the letter, in ounces? 1.5 What is the size of the letter? (L -large, R regular) 1 The postage for a large letter weighing 1.50 ounces is $ 1.15 What is the weight of the letter, in ounces? 2.1 What is the size of the letter? (L = large, R- regular) r The postage for a regular letter weighing 2.10 ounces is s 0.85 What is the weight of the letter, in ounces? 9 The total cost of postage is $4.50 You must submit the following electronically to BlackBoard: Program development-math, pseudocode, C++ code Source code-a working C++ source code