If ΔABC ≅ ΔDEF by SSS and AB = 5x + 6 and DE = 3x +10, then what must be the value of x?

On new year's day, the average temperature of a city is 5.7 degrees celsius. but for new year's day 2012, the temperature was 9.8 degrees below the average. i) if a represents the average temperature on new year's day and 7 represents the temperature on new year's day 2012, what formula accurately relates the two values together? ii) what was the temperature on new year's day 2012? dt a 0.8 ii) - 4 1 degrees celsius da-t-98 ii) 59 degrees celsius 1) 7 = -9,8 11) 59 degrees celsius ii) l degrees celsius

Anyone know? will mark brainliest if correct!

Solve for x: 5/3 x = 20/21 it's fraction. remember to simplify your fraction