How do u tell what ton a/c unit u have model cpke 30-18 goodman rla 14.7 lra 73.0 r-22 gas

You will see the number on the model or serial number on the condensing unit outside. The number will be in multiples of 12 because 12,000 BTUs is one ton. If a model number is: MKL30X578, for example, the 30 will indicate 2 1/2 tons. The numbers are: 18, 24, 30, 36, 42, 48, 54 (rare), 60, 90, 120... These equal 1 1/2, 2, 2 1/2, 3, 3 1/2, 4, 4 1/2, 5, 7 1/2, and 10 tons.