In one phase of a cycling race, a cyclist has covered three fifths of the total distance. If there are still thirty km left, what's the total distance of the race?

Step-by-step explanation:

3/5 are done, that means 2/5 are still to do.

that means these 30 km are these 2/5.

2/5 x = 30

2x = 150

x = 75

the total distance is 75 km.

  or  

step-by-step explanation:

if the four friends split the cost, p, of the pizza evenly, then each friend pays one-fourth of the cost of the pizza.

the expression is   or