4. The sum of the first 4 terms of an arithmetic progression is 36 and the 11th term is 43. Find the first term and the common difference of this progression and also find the sum of the first 15 terms.
4. The sum of the first 4 terms of an arithmetic progression is 36 and the 11th termis 43. Find the first term and the common difference of this progression and alsofind the sum of the first 15 terms.