What is the substitutions of 2a+3c=5a+2c=1

The polygon tool to draw a rectangle with a length of 5 units and a height of 3 units. one of the sides of the rectangle falls on line ab , and the rectangle has a vertex of a. each segment on the grid represents 1 unit.

Look at this pattern ; 1,4,9, number 10000 belongs in this pattern . what’s the place of this number?

Tim's phone service charges $26.39 plus an additional $0.21 for each text message sent per month. if tim's phone bill was $31.64, which equation could be used to find how many text messages, x, tim sent last month?