The cost of 40 litres of petrol is £42.40. Work out how much it would cost for 70 litres of petrol. Please help me I will give brainliest and 5 stars!!

What is the best approximation for the area of a circle with a radius of 4 m ? use 3.14 to approximate pi

Which of the following is the best first step in solving the equation below? 4+2㏒³x=17

Ariana starts with 100 milligrams of a radioactive substance. the amount of the substance decreases by 20% each week for a number of weeks, w. the expression 100(1−0.2)w finds the amount of radioactive substance remaining after w weeks. which statement about this expression is true? a) it is the difference between the initial amount and the percent decrease. b) it is the difference between the initial amount and the decay factor after w weeks. c) it is the initial amount raised to the decay factor after w weeks. d) it is the product of the initial amount and the decay factor after w weeks.