 
<translate> Bayyana tsarin tunani mataki-mataki sannan kuma amsar karshe. Yakubu ya ɗauki gwaje-gwaje huɗu a cikin darasin kimiyyar lissafi kuma ya sami 85, 79, 92 da 84. Menene dole ne ya samu a gwaji na biyar da na ƙarshe don ya samu matsakaicin maki 85? <eng> Give the step-by-step reasoning process and then the final answer. Jacob takes four tests in his physics class and earns 85, 79, 92 and 84. What must he earn on his fifth and final test to have an overall average of 85? 