Adealer buys some pens from a wholesaler at the rate of 30 rupees per pen and marked them at 40 rupees each

Serena is making an experiment. for that, she needs 20 grams of a 52% solution of salt. she has two large bottles of salt water: one with 40% and the other with 70% of salt in them. how much of each must she use to make the solution she needs? i am in need of

Heather is a cashier. she can ring up 1212 customers in 99 minutes. at this rate, how many minutes does it take her to ring up 44 customers?

Me find the answers and explain the process to find the answer of the problem appreciate it : )