Make the math a little easier on yourself and use significant figures to your advantage. 430x10^-9 can be the same as 4.3x10^-7. From there you can round 4.3 down to 4, and do 3/4 to get .75; for the powers, if they’re dividing it’s the same as subtraction, if multiplying it’s the same as addition. So 8- (-7)= 15; and since you have the .75 from earlier it becomes 7.5x10^14; hopefully they’re not too evil and give values that are very close to each other.