Answer:
ab=4c
Explanation:
Basically, if you see any variables that are together like that or numbers side by side with letters, it means it's just being multiplied! This doesn't however, work with numbers next to numbers. So for example:
Say you have a x b = 5 x 5c
It would be ab = 5 x 5c Because only letters get put next to each other. That's really the only way I know how to explain it. Have a great day and good luck!